Reinforcing elements for poured concrete, such as steel rebar or wire frame mesh, are relatively heavy and require support from what are known in the industry as chairs and clips. In the case of rebar, the reinforcing elements are often laid out in a grid with longitudinally extending bars intersecting, typically at 90-degree angles, with other bars. At the intersection points, the bars are preferably connected together, or tied with wire, or clips, and supported by chairs at a pre-determined height from the supporting surface, such as the ground, or preferably a compacted aggregate for a poured pad, provided as a base for the poured concrete. In the case of wire mesh, the reinforcing elements are already welded together at the points of intersection, so there is no need to tie each intersection together manually with a clip, though there often is the need to tie a sheet of mesh to other sheets of mesh. Thus, the primary objective of such a device as used with wire mesh is to clip to and support the wire mesh on the supporting surface.
Prior means for supporting and tying rebar has literally included blocks and bailing wire, respectively. In more recent times there have been developed devices particularly suited for the purpose of supporting and connecting rebar or supporting wire mesh. For example, U.S. Pat. No. 5,107,654 to Leonardis discloses a support chair for supporting reinforcement for foundations in which there is a turret shape and a lower base, the turret shape having a plurality of upwardly open slots into which the reinforced rods may be located, the shape of each of the slots being such as to provide for interlocking of each rod particularly by providing a narrower part of the slot through which the rod must squeeze to a lower wider part. As another example, U.S. Pat. No. 3,788,025 to Holmes likewise discloses a chair for supporting in right angular relation two reinforcing rods used in construction and comprising a lower arched base part and an upper rod supporting part. Leonardis and Holmes provide a device for support and tying of rebar or support of mesh of a single particular size, but not of two different sizes using the same device. Further, neither Leonardis nor Holmes makes provision for easy stacking and interconnection of multiple of the same type of chairs.
Another prior device used to interconnect rebar at normal intersections of the rebar, one rebar positioned above another, is found in U.S. Pat. No. 6,276,108 to Padrun, which teaches a device for supporting and connecting reinforcing elements for concrete structures comprising a circular base adapted to rest on a supporting surface, an upright post extending from the base, and a clip mounted on the post having a pair of orthogonal sockets engagable with two horizontally extending reinforcing elements, such as rebar, for connecting the elements together at right angles to each other and holding the elements a predetermined distance above the supporting surface. Padrun also discloses and claims a plurality of tapered vanes extending upwardly from the base and intersecting along a centerline of the device for supporting the post in supporting the clip for holding the reinforcing elements. Thus, Padrun provides a device for support and tying of rebar or support of mesh of a single particular size, but not of two different sizes using the same device. Further, Padrun does not make provision for easy stacking and interconnection of multiple of the same type of chairs.
U.S. Pat. No. 5,937,604, to Bowron, discloses a concrete form wall spacer for supporting a plurality of concrete reinforcing materials relative to each other within a wall. Bowron also discloses an embodiment that includes removable clips from a primary truss structure to allow customization of the device for supporting reinforcing materials. Bowron does not disclose a singular device capable of accommodating multiple cross-section sizes of reinforcing materials that is also stackable on another such singular device, and having the same identical configuration as the first device, for the purpose of supporting the reinforcing materials in multiple levels on a base for a thicker concrete pour.
U.S. Pat. No. 4,644,727 to Hanson et al. discloses a strand chair for supporting pre-stressing cable of one cross-section dimension and cross-mesh of another cross-section dimension, in an elongated precast concrete plank. However, as it discloses at least two different configuration parts for stacking, Hanson does not disclose a single device capable of stacking on itself to accomplish multiple levels of support for thicker concrete pours.
U.S. Pat. No. 7,810,298 to Kelly discloses a pair of stackable paving risers for supporting rebar in stacked and/or intersection relationship. With Kelly, an upper riser is disclosed having an extra clip member specially adapted for interconnecting a bottom portion of the upper riser to a top portion of a lower riser. The lower riser of Kelly does not include this extra clip member adapted for interconnecting the two risers. Accordingly, Kelly does not disclose a single chair capable of stacking on itself.
Strength and stability of the supporting chairs and clips is at a premium, since the chairs and clips must be strong and stable enough to withstand the weight of the rebar and wire mesh. Further, oftentimes workers walk on the framing structure of the tied and supported reinforcing materials, adding to the amount of weight that the chair and tie devices supporting the reinforcing materials must be able to withstand. Still further, the process of constructing a reinforcing framework for poured concrete is often awkward, requiring a lot of lifting of materials by workers, moving, tying and the like. As sometimes heavy bars or other materials are dragged across the framework, it is not uncommon for the chairs to tip over or even collapse or buckle under the weight of the load.
Also, from time to time there has been a need to pick up the reinforcing elements to move them after they have been placed in prior art supporting devices. For these reasons, and because other shifting can cause the reinforcing element to become dislodged from the chair or clip, the Leonardis and Padrun disclosures teach gripping of the reinforcement elements. This allows that the support chair and clip will be moved with the reinforcing elements as they are moved. Nevertheless, this also contributes to the need for stability, durability and strength of the devices, as shifting, tipping, and re-positioning of the entire framework could lead to some slight movement out of perfect alignment of one or more supporting devices.
Compounding the problems mentioned above associated with strength and stability of chairs, often times it has been desirable to have multiple layers of reinforcements stacked, as it were, for reinforcing thicker concrete pours. In such cases the bottom layer of chairs has been required to withstand the stress of two or more layers of reinforcing materials, as well as the weight of workers from time to time. Such chairs have been made of a relatively rigid yet deformable plastic in the past. There is a manifest need over the prior art for a light-weight, but sturdy and somewhat deformable, design of chair capable of strength to securely retain heavy and unwieldy concrete reinforcing members in place, yet pliable enough to admit the retaining members within a clip portion of the chair but also allow removal of the chair as may be necessary.
There are a relatively large number of sizes and combinations of chairs and clips on the market associated with differing diameters of rebar and mesh, as well as for differing heights for various thicknesses of concrete pours. For example, it is not uncommon in the industry for there to be #4, #5 and #6 rebar, corresponding to ½ inch, ⅝ inch, ¾ inch rebar, and larger sizes as well, together with chairs designed for positioning the rebar, or mesh, at the middle of a pour that is two, three, four, five, six or eight inches in depth. Thus, to be efficient, it would be desirable to simplify the number of devices from which to choose. The prior art has not provided a single device that is multifunctional in that it allows support and tying of two pieces of rebar, or alternatively, clipping onto and support of wire mesh, all at the appropriate height for the particular reinforcement material in use.
When used for reinforcement of concrete used in tilt-up construction, some prior art reinforcement support devices have also had the undesirable feature that when the dried and cured concrete has been tilted up to form a wall of the structure, the bases of the reinforcing material supporting devices have been visible on the exterior of the wall. This has caused an unsightly appearance on the surface of the wall and has also made final finishing of the wall more difficult.